A conventional parking assisting device which assists parking of a vehicle in a parking space is known. The conventional parking assisting device includes a detection unit to detect a parking space, a storage unit to store information of the detected parking space, a parking assisting operation starting unit to start a parking assisting operation, and a control unit. The control unit always performs detection of the parking space. When the parking assisting operation starting unit is set in an ON state, the control unit performs the parking assisting operation that is required to guide the vehicle to the parking space. Refer to Patent Document 1. Patent Document 1: Japanese Laid-Open Patent Publication No. 2003-081041